Dial indicator bore gauge



Oct. 19, 1954 ElSELE DIAL INDICATOR BORE GAUGE Filed Feb. 27, 1951 4 I II Snnentor Patented Oct. 19, 1954 UNITED STATES at N1 QFFI'CE DIAL INDICATOR BEBE GAUGE Andrew Eisele, Detroit, Mich.

Application February 27, 1951, Serial No. 212,956-

7 Claims. I

Thisinvention relates to bore gauges.

One object of. this invention is to provide a bore gauge which. can be quickly and easil inserted in a bore to be measured. and which will instantly indicate the. diameter of the. bore or the variation thereof. from the desired or standard. diameter.

Another object is to provide a bore gauge. of. the. foregoing character which indicates the diameter of. the-bore without requiring rocking or tilting, of the instrument to and. froin order'to obtain the measurement.

Another object isto.v provide a bore gauge of the foregoing. character wherein the bore gauge may be. tilted the full width of its. contact pin or measuring pin without causing any error.

Another object. is to provide a bore gauge wherein the stem. of the instrument is provided with a permanently mounted checking ring which is movable into and out of engagement with the head of the instrument in order to periodically check the accuracy of reading of the instrument and. adjust its-scale to a true zero reading. position.

Another object is to provide a bore gauge of. the foregoing, character which is suitable for high production work which. calls for repeated measurements of. bores of substantially the same diameter.

In the drawings:

Figure 1. is a side elevation of a bore gauge according to. one form of the. invention, with the checking ring and the motion-transmitting mechanism partly broken away to disclose its construction more clearly, and with the checking ring-retracted from its checking position;

Figure 2 is a fragmentary top plan view of the outer or left-hand end of the bore gauge shown in Figure 1;

Figure 3 is a fragmentary vertical section through the motion-transmitting mechanism taken along the line 3-3 inFi'gure 1;

Figure 4 is a rear elevation of the stem. of' the instrument shown in Figure 1, showing its connection to the motion-transmitting rod;

Figure. 5 is a fragmentary top plan: view of the mechanism shown in Figure 4;

Figure 6 is acentral vertical section through. the-outer end and head of the bore gauge taken along: the line 6-6 inFigure 2;

Figure7 is a cross-section-throug-h the measuring head of the bore gauge, taken along the zigzag line- 1-1 in Figure 6; and

Figure 8 is a. horizontal section. through the measuring. head of. the bore gauge taken along the line 8.--8 in; Figure 6.

2. Hitherto, in they use. of. ordinary bore gauges equipped with measuring pinsfor measuring the diametersof bores,.it has been. necessary to rock.

the instrument to and fro before recording the measurement in order to avoid. errors in the reading of theinstrument. In. high production work, where. measurements are made. successively of bores intended to be of' the same diameter, such as, for example, the measurement of bores. in automobile engine cylinder'bl'ocks on a production line, such rocking of ordinary bore gauges consumes valuable time which the inspectormight profitably use for other measurements. The present invention provides a bore gauge in which this rocking is substantially eliminated and in which the usual fixed measuring pins and equalizingv pins are dispensed with. Moreover, the instrument carries its own checking standard inv the form. of a checking ring, having a bore therein of'the intended diameter of the. produc-- tion bores. and movable into and out of engagement with the measuring head in order that the scale of the instrument, which is rotatab-ly mountecLcan be accurately set with its zero coinciding with the indicating needle of the dial indicator.

Referring; to the drawings in detail; Figure 1 shows a bore gauge, generally designated i0; according to one form of the invention as includinggenerally a dialindicator ll mounted in a handle I2 which also holds the rearward end of a stem [3 carrying a measuring head unit 54, a checking. ring. 55 being movably mounted on the stem [3. so as to be brought into and out of checking engagement with the measuringhead M for'periodically checking its zero setting.

The dial indicator I I isof a conventional com struction and its details lie outside the scope. of the present invention. For the purposes of the present description, it is sufiicient to state that the dial indicator H has a casing l6 mounted on a tubular stem i'i which isinserted in a. bore H8. in. the handle I2 and. which abuts an annular shoulder 1.9, between. the bore 18 and a smaller coaxial bore: 20. The inner end portion of the stem H is provided. with a bore. 2!. in which isreciprocab-ly mounted. anenlarged pin 22 carried on the lower end of a rod 23: and. urged through.

the. bore 20. by a coil spring 7.4. The. nod 23 passes upward through a smaller. bore 25 which; iscoaxial with the bore 2.! and transmits motio-ni to. the: dial indicator mechanism. (not shown) within. the casing It to a rotary shaft 26- upon which. ismounted an indicating needle 2.1-. A. dial 28. carrying an. arcuate measuring scale- 2%- is rotatably mounted upon the casing it so that it can be rotated by the user to readjust its zero point relatively to the needle 27. The dial 28 is rotated by means of a knurled bezel 3B in which the crystal 3! of the dial indicator I l is mounted. Thus, any motion of the pin 22 is transmitted to the needle shaft 25 and needle 21' so as to be indicated on the movable scale 29.

The handle it is of a shape convenient to be gripped in the palm of the hand and contains a pair of coaxial bores 32 and 33 of different diameters, the bore 33 forming a chamber into which the end portion of the pin 2?. projects. The end 34 of the pin 22 engages a flattened por tion 35 on the inner end of a motion-transmitting rod Or shaft 35, the flattened portion 35 (Figure 3) being located substantially on a diametral plane or" the motion-transmitting rod 36. The motion-transmitting rod 35 is rotatably mounted in a bore 3'! in the tubular stem !3. In order to secure these members to one another, the inner end of the tubular stem. i3 is provided with a dovetail transverse slot and the rod 35 with an annular groove 35 aligned therewith (Figure a U-shaped connecting or coupling member 69 being inserted in the dovetail slot 38 with its parallel legs passing through the annular groove 39.

The outer end of the motion-transmitting rod or shaft 36 is provided with an axially-directed projection 41 (Figures 6 and 7) of wedge-shaped cross-section and having opposite faces 62 and 43. The projection ll extends into a transverse slot 34 in a movable measuring pin 45 which is reciprocable to and fro in a transverse bore d5 of the ball-shaped portion ll of the measuring head It. The axis of the bore 46 is perpendicular to the axis of the bore 3'! in the stem [3, and the pin 35 is urged outwardly by a helical spring 48 mounted in the inner end of the bore 46 and having its opposite ends abutting the lower end 43 of the bore and the inner end 5d of the measuring pin 15 respectively. The slot 44 is of a Width substantially equal to the thickness of the wedgeshaped projection ll at its thicker end. This construction (as will be seen from Figures 6 and 7) enables the pin 45 to transmit motion to the motion-transrnitting rod 38 substantially without backlash, since the contact edges at the thicker end of the projection M substantially simultaneously engage the opposite contact sides or the slot id and the Wedge-shaped form of the projection ii permits relative motion therebetween. Due to the substantial absence of backlash, an instant response of the motion-transmitting rod 35 is obtained upon motion of the measuring pin 5. The outer surface 55 of the ball-shaped portion t! is of spherical shape and on the side thereof diametrically opposite the measuring pin 35 has a socket 52 therein coaxial with the bore fit and receiving a wear-resisting button 53 of hard material such as tool steel, tungsten carbide or the like, and having an outer surface 5&- which is of the same radius of curvature as the spherical surface 5i and forms a continuation thereof. The stem I3 is preferably made of a diameter only slightly less than the diameter of the head Hi.

Similarly, the outer end of the movable measuring pin 15 is provided with a socket 55 in which is seated a second button 56 likewise of Wearresisting material similar to that of the button 53 and having an outer surface 5? of the same radius of curvature as the spherical surface 5!. The ball portion 4'! is preferably of a diameter only slightly less than the diameter of the bore which the gauge id is intended to measure, this difference in diameter preferably being of the order of a few thousandths of an inch. The spherical surfaces 5d and 5? of the two buttons 53 and 5d are thus disposed substantially in an equatorial zone of spherical curvature of constant radius transverse to the stem [3 and er;- tending entirely around the head id.

Slidably mounted on and along the tubular stem i3 is the standard checking ring is. This is in the form of a cylindrical body of metal having a large bore 58 of the exact diameter which the gauge is intended to measure and a smaller coaxial bore of slightly larger diameter than the stem 53 in order to permit the checking ring E5 to be rocked slightly relatively to the stem ii The checking ring id is drilled as at 60 to receive a ball detent 5! which is pressed into frictional engagement with the stem [3 by a helical spring 52. A threaded, plug 63 threaded into a counterbore Eli coaxial with the drilled hole or bore fill serves as an abutment for the spring 62. The outer surface 55 of the checking ring if: is prcfera-bly knurled or otherwise roughened so as to enable it to be grasped without slipping. The stem [3 is held in the bore 32 by a set screw E38 threaded into a threaded hole 69 and engaging a depression H3 in the stem 13 in order to properly locate these parts relatively to one another.

In the operation of the invention, let it be assumed that the head 15-, as stated above, has been made only a few thousandths of an inch smaller in diameter than the diameter of the bore to be measured. In order to set the zero of his gauge, the operator grasps the handle [2 in one hand and the check ring 15 in the other hand, sliding the check ring l5 along the stem is until its standard diameter bore 58 passes over the measuring head It, as shown by the dotted lines in Figure 1, forcing the measuring pin .5 inward to a position which would cause the dial indicator H to read zero. The looseness of fit of the bore 59 on the stem 53 provides a self-alignment of the checking ring 15 relatively to the measuring head I 4. The inward motion of the measuring pin 15 causes the upper side wall 66 of the groove M to engage the edge of the upper face 42 of the wedge-shaped projection 4!, rotating the motion-transmitting rod or shaft 36 around its axis and compressing the spring 68.

The rotation of the shaft 35 rotates its flattened portion 35 located within the bore or chamber 33 within the handle !2, converting its rotary motion to reciprocatory motion of the pin 22 by the engagement of the edge of the flattened portion 35 with the lower end 34 of the pin 22 (Figure 3). This motion is transmitted upward through the rod 23 and the dial indicator mechanism (not shown) to the needle shaft 26, rotating the latter and swinging the needle through an angle. If the tip of the needle 27 does not coincide with the. zero marking or graduation upon the arcuate scale 29, the operator grasps the bezel 30 and rotates the dial 28 and scale 25-; until this condition is fulfilled. The instrumentis then ready for use and the operator ac cordingly slides the checking ring l5 away from its dotted line position over the measurin head 44 into its retracted position shown in Figure 1, where it is held in position by the frictional engagement of the ball detent 61 with the stem 13.

. 5 To measure a bore, the operator grasps the handle 12 inone hand and thrusts the measuring' head i i downward into the bore, which is assumed to be of a diameter within a few thousandths of an inch of the diameter of the ball portion 5 5 as-previously stated. Since there are no fixed measuring'pins or equalizing pins to be accurately located, the instrument does not need to be rocked and, since the stem i3 is only of slightly smaller diameter than the bore to be measured, it cannotbe" tilted through more than a slight angle before it encounters the edge of the borebeing measured.

As the measuring head i enters the boreto be measured, the side wall of the. bore forces the movable measuring pin t5 inward, this motion being transmitted to the dial indicator needle 27 and indicated on the scale 2-9 in the manner described above in connection with the use of the checking ring [5 for settin the zero of. the instrument. If the tip of the needle 2? comes to rest upon the zero graduation of the scale 29, the hole or bore being'measured is of exactly the intended diameter which, ofv course, rarely hap pens. Ordinarily, therefore, the tip of the needle 27 comes to rest on a graduation of the scale .28

which is to one side or the other of the zero graduation thereof, thus indicating a plus or minus value by which the bore being measured actually difiers from the intended diameter of the bore.

Thus, the measuring operation merely requires the operator to thrust the measuring head [4 into each hole, record the indicated reading of the needle 2'! upon the scale 29, and then withdraw the measuring head It and insert it in another bore. In this way, the bores can be measured more rapidly and with greater accuracy than with bore gauges hitherto employed. In order to insure that the instrument is reading accurately, the operator from time to time checks the zero setting by means of the checking ring it in the manner described above, so that the instrument is always maintained in a correctly set position. Since the checking ring i5 is permanently mounted upon the stem it, it cannot get lost and misplaced, hence there is a greater likelihood of the instruments being frequently checked than if a separate checking ring is employed for this purpose.

What I claim is:

1. In a dial indicator bore gauge, an elongated hollow support, a measuring head of generally spherical shape mounted on said support and having a radially-directed bore therein disposed transversely to the axis of said support, a movable measuring pin reciprocably mounted in said bore, and an elongated motion-transmittin element movably mounted in said support and having its opposite ends operatively connected in motion-transmitting relationship to said measuring pin and to said dial indicator respectively, the outer end surface of said movable measuring pin and the surface of said head in an equatorial zone transverse to said support extending entirely around said head and including said movable measuring pin having a spherical curvature of constant radius which is equal substantially to but slightly less than the radius of the bore intended to be measured by the gauge.

2. In a dial indicator bore gauge, an elongated hollow support, a measuring head of spherical shape mounted on said support and having a radially-directed bore therein disposed transversely to the axisof said support, said head havinga substantially continuous spherical surface thereon with the different portions thereof dis..--

posed stationary relatively to one another, a movable measuring pin reciprocablymounted in said bore, and an elongated rotatable motion-transmitting element rotatably mounted in said support-and'having its opposite ends operatively connected in motion-transmitting relationship to said measuring pin and to said dial indicator re-- spectively, the side of said head diametrically opposite said measuring pin being of spherical curvature of substantially the same radius and" forming a continuation of the curvature of said head, said measuring pin havingsubstantially flat sp'acedparallel contact surfaces thereon and one end of saidmotion-transmitting'element having' a projection ofwedge-shaped cross section With contact edges thereon engaging said flat contact surfaces,

3. In a dial" indicator boregauge, an elongated hollow support, a measuring head of spherical shape mounted on said support and having a radially-directed bore therein disposed transversely to the axis of said support, said head having a substantially continuous spherical surface thereon with the diiferent portions thereof disposed stationary relatively to one another, a movable measuring pin reciprocably mounted in said bore, and an elongated rotatable motiontransmitting element rotatably mounted in said support and having its opposite ends operatively connected in motion-transmitting relationship to said measuring pin and to said dial indicator respectively, the side of said head diametrically opposite said measuring pin being of spherical curvature of substantially the same radius and forming a continuation of the curvature of said head, said measuring pin having therein a recess with substantially fiat spaced parallel contact surfaces and one of said motion-transmitting element having a projection thereon having opposite substantially fiat surfaces inclined at an acute angle to one another and forming a wedge of substantially the same base thickness as the width of said recess, the base of said wedge having contact edges engaging said flat contact surfaces of said recess.

1. In a dial indicator bore gauge of the type having an elongated hollow stem carrying a measuring head with a movable measurin pin therein operatively connected by motion-transmitting mechanism to said dial indicator, a gauge checking device comprising a body having a bore slidably receiving said stem and a counterbore, said body being movable along said stem into a position extending over said measuring head, said counterbore having a predetermined diameter corresponding to a selected reading of said dial indicator.

5. In a dial indicator bore gauge of the type having an elongated hollow stem carrying a measuring head with a movable measuring pin therein operatively connected by motiontransmitting mechanism to said dial indicator, a gauge checking device comprising a body having a bore slidably receiving said stem and a counterbore, said body being movable along said stem into a position extending over said measuring head, said counterbore having a predetermined diameter corresponding to a selected reading of said dial indicator, and a detent device disposed in said body and detainably enaging said stem.

6. In a dial indicator bore gauge, an elongated hollow support, a measuring head mounted on said support and having a bore therein disposed transversely to the axis of said support, a movable measuring pin reciprocably mounted in said bore, and an elongated rotatable motion-transmitting element rotatably mounted in said support and having its opposite ends operatively connected in motion-transmitting relationship to said measuring pin and to said dial indicator respectively, said measuring pin having substantially flat spaced parallel contact surfaces thereon and one end of said motion-transmitting element having a projection of wedge-shaped crosssection with contact edges thereon engaging said fiat contact surfaces.

'7. In a dial indicator bore gauge, an elongated hollow support, a measuring head mounted on said support and having a bore therein disposed transversely to the axis of said support, a movable measuring pin reciprocably mounted in said bore, and an elongated rotatable motion-transmitting element rotatably mounted in said sup port and having its opposite ends operatively connected in motion-transmitting relationship to said measuring pin and to said dial indicator respectively, said measuring pin having therein a recess with substantially flat spaced parallel contact surfaces and one end of said motion-transmitting element having a projection thereon having opposite substantially flat surfaces inclined at an angle to one another and forming a wedge of substantially the same base thickness as the width of said recess, the base of said wedge having contact edges engaging said fiat contact surfaces of said recess.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,157,389 Hess Oct. 19, 1915 1,385,495 Tangen July 26, 1921 1,656,180 Eisele Jan. 1'7, 1928 2,179,538 Boehnke Nov. 14, 1939 2,362,808 Durgin Nov. 14, 1944 2,376,118 Brown May 15, 1945 2,454,159 Graves Nov. 16, 1948 2,484,697 Eisele Oct. 11, 1949 FOREIGN PATENTS Number Country Date 291,286 Great Britain May 31, 1928 

